RFR: 8317965: TestLoadLibraryDeadlock.java fails with "Unable to load native library.: expected true, was false"

[Mandy Chung]

`TestLoadLibraryDeadlock.java` test runs `LoadLibraryDeadlock` and wait for 5 seconds and then grab the output. Then run `jcmd` to dump the thread stacks in case there is a deadlock. The test ignores and swallows any exception which makes it hard to diagnose test issues. 

This PR simplifies the test to use `jdk.test.lib.process.ProcessTools` to launch `LoadLibraryDeadlock` test so that the output and error will be captured in the same way as other tools are run by this test.   Also update the test to propagate exceptions where appropriate.   This hopes to collect more information to diagnose the issue if this test fails next time.

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Commit messages:
 - 8317965: TestLoadLibraryDeadlock.java fails with "Unable to load native library.: expected true, was false"

Changes: https://git.openjdk.org/jdk/pull/16459/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16459&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317965
  Stats: 69 lines in 2 files changed: 5 ins; 57 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/16459.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16459/head:pull/16459

PR: https://git.openjdk.org/jdk/pull/16459